The invention relates to a trimming unit for use in conjunction with a personal care appliance, such as a dry-shaving apparatus or a hair clipper. Such a unit comprises a frame, a stationary cutter which is disposed at the frame and provided with teeth at its front, a movable cutter which engages with the stationary cutter and is provided with teeth near those of the stationary cutter, a spindle, which is disposed at the frame at some distance from and parallel to the toothed front side of the stationary cutter, a coupling member, which is disposed at the spindle and which is both longitudinally reciprocatable relative thereto and pivotable about it, which member can be coupled to the movable cutter at some distance from the spindle and furthermore comprises parts for coupling to a drive motor, and resilient means which include a helical wire spring which is disposed around the spindle, which spring near its ends comprises extensions of which a first extension, at some distance from the spindle, presses on the coupling member and thus presses the cutters into engagement with each other.
A trimming unit of this type is known from Swiss Patent No. 403,551, disclosing a trimming unit which as a separate attachment can be fitted on a housing which accommodates a drive motor. The stationary trimming cutter is rigidly connected to a plate which in its turn is coupled with appropriate parts of the housing. This plate forms a part of the frame on which also the spindle is disposed about which and over which the coupling member for driving the reciporcating trimming cutter is pivotable and slidable respectively. The coupling member is substantially shaped as a two-armed lever whose arms make an angle with each other. One arm cooperates with the reciprocatable trimming cutter, and the other arm serves for driving the coupling member. The two arms are not rigidly connected to each other but are pivotable to a limited extent about the spindle relative to each other. The helical spring which is disposed around the spindle, with its first extended end, presses against the lever which serves for coupling to the movable cutter and with its other extended end against the arm which serves for driving. In the situation in which the trimming unit is not attached to the housing of the appliance, the two arms are pressed apart by the spring into a position in which mutual stops prevent the angle between the two arms from increasing any further. In the situation in which the unit is attached to the appliance, the drive pin which extends from the housing and which is connected to the drive motor presses the lever for the trimmer drive a little way into the direction of the other lever. As a result of this, the spring exerts a certain pressure on the other lever, which pressure is imparted to the movable trimming cutter and by said cutter to the stationary trimming cutter, so that the two trimming cutters are pressed firmly against each other.